In short, Android is more of a bet on the past — in which there are locally installed applications, and Chrome OS is a bet on the future — in which all applications are remotely delivered through the browser. Chrome is important to Google because it serves as a portal to everything, both data and applications.

"We are expanding computing to many things," Google SVP of Chrome, Apps, and Android Sundar Pichai told Fortune. "Increasingly, as you have more computing devices in your life, you want it all to work together. You want these screens to work together in ways that make sense to you. I feel we are uniquely positioned because we have two great tools, in Chrome and Android, two large open platforms, with which we can bring these things together to solve problems focusing on the user."

Chrome complements Android in a multiscreen world, Pichai says. That's because Pichai sees Chrome OS as a proponent for Web technologies, playing a "critical role in making sure that in a multiscreen world, those screens work together in harmony and work together for users."